LF3330
DEVICES INCORPORATED
Vertical Digital Image Filter
programmable. This allows the filter’s
output to be rounded to any precision
required. Since any 32-bit value may
be programmed into the round
registers, the device can support
complex rounding algorithms as well
as standard half-LSB rounding. RSL
3-0
determines which of the sixteen round
registers are used in the rounding
operation. A value of 0 on RSL
3-0
selects round register 0. A value of 1
selects round register 1 and so on.
RSL
3-0
may be changed every clock
cycle if desired. This allows the
rounding algorithm to be changed
every clock cycle. This is useful when
filtering interleaved data. If rounding
is not desired, a round register should
be loaded with 0 and selected as the
register used for rounding. Round
register loading is discussed in the
LF Interface
TM
section.
Output Select
The word width of the filter output
is 32 bits. However, only 16 bits
may be sent to DOUT
15-0
. The select
circuitry determines which 16 bits
are passed (see Table 1). There are
sixteen select registers which control
the select circuitry. Each select
register is 5 bits wide and user-
programmable. RSL
3-0
determines
which of the sixteen select registers
are used in the select circuitry.
Select register 0 is chosen by loading
a 0 on RSL
3-0
. Select register 1 is
chosen by loading a 1 on RSL
3-0
and
so on. RSL
3-0
may be changed every
clock cycle if desired. This allows
the 16-bit window to be changed
every clock cycle. This is useful
when filtering interleaved data.
Select register loading is discussed
in the LF Interface
TM
section.
3 set to “0”. Any LF3330s cascaded
after the first LF3330 should have
Bit 0 of Configuration Register 3 set
to “1”. When not cascading, Bit 0 of
Configuration Register 3 should be
set to “0”.
It is important to note that the first
multiplier on all cascaded devices
should not be used. This is because
the first multiplier does not have a
line buffer in front of it. The coeffi-
cient value sent to the first multi-
plier on a cascaded device should be
“0”.
Rounding
The filter output may be rounded by
adding the contents of one of the
sixteen round registers to the filter
output (see Figure 4). Each round
register is 32 bits wide and user-
F
IGURE
6. C
OEFFICIENT
B
ANK
L
OADING
S
EQUENCE
COEFFICIENT SET 1
COEFFICIENT SET 2
COEFFICIENT SET 3
CLK
W1
LD
W2
W3
CF
11-0
ADDR
1
COEF
0
COEF
7
ADDR
2
COEF
0
COEF
7
ADDR
3
COEF
0
COEF
7
W1: Coefficient Set 1 written to coefficient banks during this clock cycle.
W2: Coefficient Set 2 written to coefficient banks during this clock cycle.
W3: Coefficient Set 3 written to coefficient banks during this clock cycle.
F
IGURE
7. C
ONFIGURATION
/C
ONTROL
R
EGISTER
L
OADING
S
EQUENCE
CONFIG REG
SELECT REG
ROUND REGISTER
LIMIT REGISTER
CLK
W1
LD
W2
W3
W4
CF
11-0
ADDR
1
DATA
1
ADDR
2
DATA
1
ADDR
3
DATA
1
DATA
2
DATA
3
DATA
4
ADDR
4
DATA
1
DATA
2
DATA
3
DATA
4
W1: Configuration Register loaded with new data on this rising clock edge.
W2: Select Register loaded with new data on this rising clock edge.
W3: Round Register loaded with new data on this rising clock edge.
W4: Limit Register loaded with new data on this rising clock edge.
Video Imaging Products
6
11/08/2001–LDS.3330-M
LOGIC [ LOGIC DEVICES INCORPORATED ]
